Some experiments are described in which a counter-spectrometer method is compared with an X-ray photographic method as a means of determining the integrated reflexion of a number of reflexions. The advantages and limitations of the photographic, ionization and counter-spectrometers are discussed, and it is concluded that for long exposures the photographic spectrometer is as sensitive as the counter-spectrometer used for a few minutes and more sensitive than the ionization spectrometer. For convenience and speed of measurement the counter-spectrometer is probably the best instrument.